Measuring and comparing intelligence, or "smartness," within and across species is not a simple task. Even defining and measuring intelligence in people is controversial. For example, how does someone define "smartness" across cultures? Consider how two people from different cultures would choose when faced with a decision of picking among a bucket, an egg shell, and a canister to use as a water container. Someone living in a modem city like Washington, D.C. would probably pick the bucket. On the other hand, a Kalahari bushman would probably pick what is most familiar to him—an egg shell. The scenario may be a better measure of how different cultures carry water than one of intelligence.
Developing and performing intelligence between different species or different kinds of animals (mammals, birds, reptiles, and fish) is even more complicated than comparing intelligence in people. Species might differ in their abilities in a number of ways:
Animals have special abilities that allow them to survive in their particular habitat. Some of those abilities that seem amazing to people don't necessarily demonstrate an animal's intelligence or ability to think. Placed in a different environment, these "amazing" abilities may prove useless. But "thinking" animals are those that can demonstrate flexibility when faced with new environments and challenges.